Electrical measuring instrument.



PATls-NTED FEB. 18, NCB.

A. H.H0YTs ELECTRICAL MEASUB-ING INSTRUM ENT APPLIOATIN FILED JULYQ, 1904.

- that the indicating needle actuated by the' ADRIAN HOYT, OF PENACOOIQNEW HAMPSHIRE, SSIG' WHITNEY ELECTRICAL INSTRUMENT COMPANY, A CORPORATION OI: NEW YORK.

ELECTRICAL MEASURING INSTRUMENT.

Specification of Letters Efatent, i

Patented Fb.- 18, 190s'.

Application filed July 9| 1904:, Serial No. 215.865

To all whom it may concern.'

Be 1t known that I, ADRIAN II. Iloi'T, citi- -zen of the United States, residing at Penacoolr,

clear, and exact specification.

My invention relates to instruments for indicating the presence or measuring `the strength of electric currents, and belongs to that class of electrical measuring instruments in which the current to be measured passes through a stationary coil and influences a relatively small and delicately poised body of magnetic material that is inductively magnetized by a stationaryfpermanent or electromagnet.' In instruments of this class as heretofore constructed, such for instance as that which is shown in a prior patent granted to me on May 16th, 1893, bearing Serial 97,522, the permissible angular rotation of the poised magnetic substance has been limited to ninety. (90) degree or less, and in order to obtain maximum sensibility, it was necessary to decrease the strength of the field provided by the magnet in order td thus reduce the restoring force,'which tendedfto bring the moving mass with its attached pointer backv to its starting or zero position, to a minimum. The instruments of this class as heretofore constructed have the further disadvantage movable magnetic body would oscillate for Isome time before coming to rest, or in other words, that they give indications which are not dead beat. p

Briey, my4 invention consists in arrangthe movable magnetic element in such a manner that, while it is polarized by the stationary magnet, the iniiuence of the station-' ary magnet does not tend to cause the movable mem'ber to assume any xed position relativetheretdyand in roviding an external directive force, such as elicalsprings, which offer an increasing resistance to the motion;

` of the needle actuated by the moving memof the scale along the scale.

whereas inolder instruments of this type the betas the needle moves from the zero point In other words,

stationary magnet not only polarized the movablemagnetic element but furnished the force which opposed the motion of that element, in my present; invention the sta-tionary inag'i'ie'tA does not perform the latter function and I am hence able to obtain high sensibility, not by weakening the stationary magnet but by proportioningit so that it will supply an intense magnetic field which will magnetically saturate the moving element, Further than this,.. the movable element in my improved instrument can rotate through an angle of nearly one hundred 'and eighty (180) degrees; and, still further, I am able by a simple expedient to dampen the oscillations of the movable element. As the magnetic iield in which the movable magnetic element is located is of great strength and as the magnetic element is magnetically saturated, it is evident that the instrument will suffer but slight disturbance from external magnetic iields such as may be due to other magnets or to current carrying conductors in the neighborhood.

The invention will be more particularly described with reference to the accompanying drawings, in which Figure l, is a side view of the working parts of an instrument embodying the invention, Fig. 2, is a plan view of the same, and F ig. 3, shows alternative shapes for the movable magnetic elements, Figs. 4 and 5 are diagrams showing the movement of the polarized element.

Like figures of reference `apply 4to like p arts The spool Ll is preferably made of two `halves to permit of the easy introduction of' the shaft 5,y `Suitably located and preferably.

within thespcol e is a pivot bearing 9 for the lower entremity of the shaft 5 vthe upper end of said shaft being similarly pivoted ena bearing provided in bracket 10. The shaft 5 carries, diagonally mounted as shown in the drawings, a short strip of magnetic material l1 (preferably iron) a sector ofconducting material 18 (preferably aluminium), volute springs 13 preferably wound in oppositedirections, one extremity of the springs hev so rotation of the shaft. I may. obviously substitute fior'. the volute springs 13, spiral springs or I may use weights or any otheroi t Le Well known ge uivalents for furnishing a force-t 'oppose t e motion of the pointer,y

which force increases in stren .th as the degre'e Lof' deflection increases. extremity of the magnet. is a strap' .16- oi" magnetic material sosha ed vasto provide a quiteintense. magnetic eld at 17 between its lower'f'ace and the upper face of the err-nl tensionZ. In this gap, the sector 18 at.`

to swings. 1Q-,is a support carrying fiscale suitably graduated. The instruis moi'inted-on a suitable base-plate.

i 'It Iseen that Whatever the position o-fhe needle 15 relative to'its scale 20, and of the, movable element 11 to the stationary magnet. '1 and. its pole pieces 2 and 3, ythe distancebetween the extremities 0f fthe' element 11 and ofthe face ofthe magl not 1' and its pole is the same, and hence no -force is exerted by the magnet to` bring the 'movableeiement to or' -hold it in a definite position.f"1`he s rmgs .13- are however so adjusted as to direct the lneedle to the zero markjo'n the 'scale-20.. When the current to measured passes throughthe coil 6 wound ort-the spool 4,the'polarized element 11 will,

3.6530165112," t0 they-well vunderstood principles if.;,ell-retro?'magnetism, endeavor to rotate and assumel a'posi-tion so vthat direction' of, magnetization will correspond with the direction .of magneti-'enunthro h the coil,

'e an'jd'thefforce with which it ten s to rotate constitutes a measure'oi the current strength. Thatforc'e isopposedbythe directive iorce ofthe:springsl/orvtheir equivalent, and, as

' that force is of a di'erent magnitude for each dierent -paaition of the'y pointer 15,I each of the-dierent pointer positions will corres ond to some-definite current stren th, an( the scale canhencebe suitably gra uated to indicate vthesecurrent strengths.l As is well understood the instrumentxshonld be wound with many-turns ci small `diameter wire when used for the measurement of electrical potentials, andwith few turns of a conductor of-large cross section when used for the measurement ofelectrical currents. hAs the position of the element 11 relative to the stationary'coil of wireI 6 may be made such,

with due vregard to the p'olarityof the ele-- ment, .jthat it must rotate about its axls nearly one hundred and eighty degrees before. f' its direction of magnetization will correspond with. the direction of magnetic flux through thef coil, itis obvious that the pointer 15 may be'caused tos'win over a scale of an are of. ne'rly'one hundre and eighty (18,0) degrees.

Figsr `11 and 2 indicate the position of the part's'pwhen thepointer is approximately at ecured to oneA erases 4 direction that the iiuX created vthereby causes the element- 11 Vto turn on its pivot and lwhen near its maximumdeiiection the element 11 will assume a position' substantially .that indicated in Fig.V 5, the element 1 1 having swung through an arc 'of nearly 150 degrees. i y e i -fDampening oi the oscillations ofthe moving system in my instrument is accomplished in that, when 'the sector 18 ofaluminium or other conducting material rigidly attached to the shaft 5, swings in the gap 17 eddy cur-` rents are'set up therein in the well known manner. It is obvious that instead' of mak.- ing the element`11 straight and mounting it at an angleon the shaftl, I may curve it as inli`ig-3., 4'

The device above described maybe modi iied-in various-respects "Without departing from-.the invention and I therefore desire it to be understoodthat I do not herein limit myself to the speciiic construction shown.

Having thus described` my invention, I declare that what I claim Vas new and desire ato secure by Letters Patent, is,'-'-

1.A In an electrical measuring instrument, the combination o'r' a magnet, a pivoted shaft, an element'mounted upon saidY shaft in the -iield ofiforce of the magnet in such manner as not to bemoved thereby, a coil carrying current adapted to rotate said element, springs o posing'the" movement of the ele- \ment, an a mass of dampening material carried by said shaft andl moving in' a magnetic iield, substantially as described.

2. In an electrical measuring instrument, Ithe combination of a pivoted inclined element, means for polarizing said "element, `mechanical means tending to hold said element in a fixed position, a coil for causing deflection of said element upon the passage cfa current, and ymeans for indicating the amount oi said deflection.

3. In an electrical measuringinstrument, the combination of a movable polarized element, stationary means for polarizing said element, a coil-adapted to receive the current to be measured, and resilient means tendingto hold said element in Va positionu such 'that its lmagnetization opposes that of the coil when said current flows. i

4. In an electrical measuring instrument, the combination of a pivoted polarized' ele-- ment, stationary means for polarizing Vsaid element, a fixed coil adapted to receive the current to be measured, and resiiientmeans tending to hold said element in a position los pivoted element polarized by said magnet, a.

Hxed coil adapted to receive the current to be measured, and resilient means tending to hold said element in la position `s'uch that its magnetizationbpposes that of the coil when said current Hows.

7. In an electrical measuring instrument, the combination of a stationary magnet, a pivoted element polarized by saidmagnet, a Hxed coil adapted to receive the current to be measured, lthe shaft carrying said element being at right angles to the axis of said coil,

and means tending to hold said elementin-'a Hxed position.

8. In an electrical measuring instrument, the combination of a stationary magnet, a pivted element polarized by said magnet, a Hxedcoil adapted to receive the current to be measured, the axis on which said 'element rotates being at right angles to the axis of said coil, and resilient means tending to hold said element in a position such that its magnetization opposes that of the magnetization of the coil when s aid current Hows.

9. Tn an electrical measuring instrument,

the combination of a 4stationary magnet, a pivoted element polarized by said magnet, a Hxed coil adapted to receive the current to be measured, the axis on which said element rotates being at right angles to the axis of said coilresilient means tending to hold said element in a positi on such that its magnetization opposes that of the coilwhen said current Hows, and means for dampening the movement of said' element.

l0. The combination of a magnet having two arms one vertically above the other, an inclined element polarized by said magnet and adapted to turn about a vertical axis, a stationary coil adapted to receive the current tol be measured, the axis of said coil being at right angles to the vertical axis of said element, and resilient means tending to hold said element in a position such that its magnetization opposes that of the coil when said current Hows.

1l. The combination with two arms of a stationary magnet, of an element adapted to rotate about an axis at right angles to said arms, said element being inclined in the direction of magnetic Huxbetween said arms, a stationary coil adapted to receive the current to be measured, the axis of said coil being at' right angles to the' axis about which said element rotates, and means tending to hold said element in a Hxed position.

In testimony whereof I aiHX my signature, in presence of two witnesses.

. ADRIAN H. HOYT.

Witnesses:

J. A. Massin, HORACE B. SHERBURNE 

